The present invention relates to a method and equipment for line-by-line recording of color component images by means of a controlled beam onto a reproduction carrier. The recording of different color component images occurs at recording stations separated from each other by at least one additional processing station.
When a plurality of color component images together constituting a reproduction of a color picture is recorded by means of a laser during continual transport of the reproduction carrier past the recording station, it is of course difficult to achieve exact superposition or registry of the color component images with each other. This is particularly difficult since each color component image must be developed prior to the recording of the next subsequent color component image. The first, second and third color component images can be displaced laterally in the line direction (i.e. horizontally displaced) from each other and/or vertically displaced from each other, that is in direction of transport of the reproduction carrier. These errors in registry can result in the creation of disturbing color fringes in the final color copy. They further decrease the possible resolution of the color reproduction.
The horizontal displacement between the various color component images and a part of the vertical displacement results from tolerances in the transport of the reproduction carrier. The main part of the lack of registry in the vertical direction is due to the rigid time coupling between scanning and recording which is not accompanied by an equally rigid coupling between the scanning and the reproduction carrier transport.
In practice it has been found that to create an acceptable reproduction, the maximum allowable lack of registry between different color component images is one-tenth of a millimeter. In electrophotographic recording equipment the distance between the recording stations is in the order of 1 meter. Since the reproduction carrier must be developed, fixed and recharged within this distance, the above-mentioned tolerance cannot be maintained.